It is well known that there are many safety concerns when working in the vicinity of moving equipment, particularly in industries such as the oil and gas industry. Precautions are taken to ensure that personnel working with, or near such equipment are protected from directly engaging and becoming entangled in the moving apparatus. Guards are placed over the moving parts.
In the case of progressing cavity pumps, a polished or coiled rod is connected to a main shaft of a drive head at surface, for rotating a rod string and rotor connected thereto, for driving the pump downhole. The rotatable rod typically extends above a rod clamp on the drive head at surface. The rod rotates with the driven main shaft.
It is known to provide a fixed safety guard to surround or enclose the exposed portion of a polished rod. Thus, the guard prevents accidental engagement with a rotating polished rod. The energy in the rotating polish rod and supported drive string is significant and rotation takes some time to arrest. Thus, by preventing contact with the rod string, injury to personnel and damage to the surface of the polished rod is minimized.
Tubular, fixed guards are known. Typically, the guard is a metal mesh or solid plastic tube which has a fixed diameter that is significantly larger than both the main shaft and the polished rod clamp to avoid engaging either the shaft or the rod during rotation. The prior art guards are affixed to the drive head, such as to a top of the gearbox and remain stationary. In drive heads where the motor is affixed to the top of the gearbox, the motor must be spaced sufficiently from the main shaft and polished rod clamp to permit mounting the guard therebetween. This may result in a larger drive head than would otherwise be required or prevent proper installation of the guard at all. Further, fixed guards must typically be custom-made for the drive head to enable affixing thereto.
There is interest in the industry for a universal safety means to prevent or minimize contact with polished rod, main shaft and polished rod clamp while maximizing space in the drive head for mounting the motor and the like.